EP4115051A1

EP4115051A1 - Blade made of multiple materials

Info

Publication number: EP4115051A1
Application number: EP21722274.4A
Authority: EP
Inventors: Rémi Philippe Guy ONFRAY; Dorian Alexandre Alban BANTWELL; Alix Thomas Bernard Lejeune
Original assignee: Safran Aircraft Engines SAS
Current assignee: Safran Aircraft Engines SAS
Priority date: 2020-04-09
Filing date: 2021-04-01
Publication date: 2023-01-11
Anticipated expiration: 2041-04-01
Also published as: US20230175402A1; WO2021205098A1; EP4115051B1; US11873732B2; FR3109181A1; CN115380153A; FR3109181B1

Abstract

The airfoil (3) of a turbomachine blade comprises a first, structural resistance part (8) made of two end portions (11, 12) including the leading and trailing edges (4, 5) and end strips of the suction face and the pressure face (14, 15, 16, 17), and a core (13) joining these. Two other parts of the blade (9, 10) are made of lightweight material, for example composite material, between the end portions in order to make up the complete airfoil. According to the invention, the core has an oblique or diagonal extension between the end portions.

Description

Title: Dawn composed of several materials

The subject of the invention is a blade made of several materials.

The constant search for lightening of turbomachines in aeronautics has also extended to blades. Various designs of hollow blades have already been proposed, but their use is not always possible. Another way to lighten the blades then consists of using lighter materials, such as composite materials; but this process also has limitations, since lightweight materials generally do not have the desired strength for the most heavily loaded parts of the blades, such as leading edges exposed to impact and wear due to entrained solid impurities. with gases; moreover, they generally do not make it possible to shape with sufficient finesse these leading edges as well as the trailing edges.

It was then proposed (this is the subject of document FR 3035679 A, among others) to reinforce a massive blade, constructed of a light material, by a reinforcement composed of a thin sheet of foil in a resistant material, which is folded. to cover the main material on a small strip of the intrados face and the extrados face. Blades that are both light and sufficiently resistant in service are then obtained. However, these local reinforcements also have certain drawbacks: the shaping of the foil is first of all difficult, because of the lack of rigidity of this thin and slender piece, and that it is necessary to shape to a complicated and irregular shape, the edges of the recent blades often having inclinations in the axial direction and the tangential direction (known as arrow and dihedral angles) which are significant and highly variable; and even constructed with a very thin sheet of tinsel, the reinforcements give pleats that are too thick and rounded to build fairly thin and sharp blade edges.

An improved blade construction, but which the invention improves upon, is also disclosed in US 3,294,366 A.

Another construction is proposed according to the invention. This comprises, according to a general definition, a blade comprising a reinforced leading edge, a trailing edge, and extending between the leading edge and the trailing edge while being limited by a lower surface and an upper surface which are two aerodynamic faces principal of the vane, opposite in a direction of vane thickness and each extending from the leading edge to the trailing edge; the blade being formed of a first part, in one piece in a first material, composed of a first end portion comprising the leading edge, of a second end portion comprising the trailing edge and of a web connecting the first end portion to the second end portion, the first end portion and the second end portion each comprising a strip of each of the main aerodynamic faces; of a second part, extending between the first end portion and the second end portion and joined to a main face of the core, in a second material lighter than the first material, and carrying an area of a first of the main aerodynamic faces between the bands of said first aerodynamic face belonging to each of the end portions; and a third part, which is, like the second part, in a material lighter than the first material, and which carries a zone of the second of the main aerodynamic faces between the bands of said second aerodynamic face which belong to the portions of end of the first part; characterized in that the web has, over at least a part of the height of the blade, an oblique extension in the direction of thickness, whereby the second part will have a greater thickness near the second portion of the blade. end than near the first end portion, and the third part a greater thickness near the first end portion than near the second end portion.

The leading and trailing edges are constructed as rigid portions of the pressure side face and the pressure side face over at least the majority of their extension, instead of being formed from curved foil sheets . One obtains at the same time a greater ease of manufacture of the leading and trailing edges thanks to the rigidity of these end portions, and the faculty of constructing the leading and trailing edges with a sharp section. The core ensures the cohesion of the whole by taking up the forces which appear in the blade. And the second part can be much larger than the first, thus allowing a significant overall reduction. Its cohesion with the first part is good, since it is disposed in a cavity formed by the latter between the end portions, which protrude from the core in the thickness direction of the blade. The mechanical resistance of the second part can be low since the forces undergone by the blade are taken up by the first: the second part is justified to re-establish a continuous main surface, and therefore of good aerodynamic quality, of the blade. The third part has the same properties as the second.

The second part and the third part can both be constructed from the second material.

The first and second end portions are often chosen to be massive (and thicker than the core in the thickness direction) to give them sufficient strength.

The considerations of resistance or rigidity with regard to the static or dynamic forces, including the vibrations, are important for the precise definition of the parameters of shape and dimensions of the blade, and here especially of the web and the first part. An important idea is that the sections of the blade taken at different radii differ as to the position of the web, which can therefore present warnings, that is to say inclinations that are uniform or not in the angular direction of the web. the turbomachine along the radial direction; or twists (rotations) around the radial direction, from one cut to another. This results in certain particular constructions, according to which:

- in sections taken through the vane, in a radial direction from the vane and from the intrados face to the extrados face and over a part of the height of the vane, one of the second part and of the third part has an increasing thickness in an outward direction of the radial direction, and the other of the second part and of the third part has a decreasing thickness in said outward direction;

- in a first section taken through the blade, adjacent to the first end portion, in the radial direction of the blade and from the pressure side face to the pressure side face and over a part of the height of the blade, one of the second part and the third part has an increasing thickness in an outward direction of the radial direction, and the other of the second part and the third part has a decreasing thickness in said outward direction; and, in a second section taken through the vane, adjacent to the second end portion, in a radial direction from the vane and from the lower surface face to the face of the extrados and on a part of the height of the blade, said one of the second part and of the third part has a decreasing thickness in an outward direction of the radial direction, and said other of the second part and of the third part has an increasing thickness in said outward direction.

Such constructions can extend over the entire height of the blade in the radial direction, or over only part of this height. Thus, according to advantageous constructions, said height portion of the blade has an extension of at least 30% in height; the height varying from 0% at a radially inner end of the vane to 100% at a radially outer end of the vane; or again, said height portion of the blade extends between the heights of 20% and 80% between these ends.

According to other construction possibilities, the second part and / or the third part has a thickness (at least over a part of the height of the blade) continuously decreasing towards zero in the direction of one of the end portions, that is, that is to say that the web can be connected to the end portions, or to one of them only, to the intrados or the extrados.

According to certain embodiments envisaged for the invention, the first end portion and the second end portion are connected to the core by rear faces, respectively opposite the leading edge and the trailing edge, which are essentially flat, and the core is a rigid plate delimited by two main and opposite faces which are smooth.

The core may also have a variable thickness from the first end portion to the second end portion, depending on its desired strength properties.

The first material will generally be metallic and chosen for its strength, while the second material (and that of the third part, if it is different from the second material) may be in composite material, or in polymer (resistant to high temperatures) for give the desired relief. The assembly of the second part and the third part to the first part will normally be easy, since they are located in a cavity or cavities of the first part, in which they can be. molded or formed, producing good cohesion by adhesion to the first part.

The invention will now be described in its various aspects, characteristics and advantages by means of the following figures, which illustrate certain embodiments thereof given purely by way of illustration: FIG. 1, a general perspective view of the blade; FIG. 2, a first embodiment of the invention, in section; FIG. 3, a section of a second embodiment; FIGS. 4A, 4B and 4C, three successive sections of a third embodiment; FIGS. 5A, 5B and 5C, three successive sections of a fourth embodiment; FIG. 6, a section of a fifth embodiment; FIG. 7, a perspective view of the fourth embodiment of the invention; Figure 8, a perspective view, in an opposite orientation, of the fourth claim; FIG. 9, a view of a possible detail of arrangement; and FIG. 10, another embodiment of such a detail.

FIG. 1 represents a general view of a vane, such as a compressor vane, to which the invention can be applied: the vane comprises an inner platform 1 at an inner radial end, an outer platform 2 at one end radial outer, and a blade 3 joining the platforms 1 and 2 and on which the invention is located. The blade 3 is intended to extend into a gas flow stream, where it can be exposed to high temperatures, as well as to impacts of various solid impurities entrained in the gas stream. It comprises a leading edge 4, a trailing edge 5, and it is limited by two curved aerodynamic faces both joining the leading edge 4 to the trailing edge 5, including an upper face 6 and a d face. 'intrados 7 opposite in the direction of thickness T of the blade 3. For each section of the blade 3, at constant radius in a radial direction R, we will consider a direction of elongation X going from the leading edge 4 to the trailing edge 5, in addition to the direction of thickness T, these three directions being perpendicular. We will also define a height parameter on the blade, measured from 0% at the inner platform 1, to 100% at the outer platform 2 in the radial direction R.

FIG. 2 details the structure of the blade 3. It is composed of a first part 8 and, in this embodiment, of a second part 9 and of a third part 10. The first part 8 has a role of structural rigidity and is normally constructed of metal. It comprises a first end portion 11, a second end portion 12 and a core 13 joining these end portions 11 and 12. The first end portion 11 comprises the leading edge 4 and two bands 14 and 15 end of the upper surface 6 of the lower surface 7, which join together at the leading edge 4. The second end portion 12 comprises the trailing edge 5 and two end bands 16 and 17 of the upper surface 6 and the lower surface 7, which join one another at the trailing edge 5. The strips 14 and 16, as well as the bands 15 and 17, however, occupy a small portion of the width of the upper and lower surfaces 6 and 7 (in the direction of elongation X). The end portions 11 and 12 are massive, that is to say they have a solid section and extend, in the thickness direction T of the blade 3, continuously from the end strip 14 or 15 from the upper surface 6 to the end strip 16 or 17 of the lower surface 7, and that they therefore occupy the entire thickness of the blade 3 at the leading edge 4 and at the edge of leakage 5 and close to them (their ends opposite to the leading 4 or trailing 5 edges respectively can however be connected by a rear face 18 or 19 planar or slightly concave, as shown here).

The core 13 is a spacer which joins the end portions 11 and 12 by their rear faces 18 and 19. It is integral with them and may consist of a plate or a rigid curved web, extending between two main faces 20. and 21 may be smooth or on the contrary stiffened. Its thickness is variable here, greater in the center than near the end portions 11 and 12. It is determined, with or without an evolution or variations between the end portions 11 and 12, as a function of the static mechanical strength. or dynamic to be obtained for the dawn, and which indeed depends a lot on the characteristics of the core 13. Anyway, the thickness of the core 13 is much more lower than that of the end portions 4 and 5, with the consequence that the core 13 occupies only a small part of the volume of the blade 3 between these portions. Abrupt thickness transitions between the core 13 and the end portions 11 and 12 are accepted, and present here.

The second part 9 and the third part 10 extend in cavities delimited by the core 13 and the end portions 11 and 12, on opposite sides of the core 13. The second part 9 is delimited mainly by the core. main face 20 of the core 13, the rear face 19 of the second end portion 12 and the strip 14 on the side of the upper surface 6 of the first end portion 11. The third part 7 is delimited by the other main face 21 of the core 13, the rear face 18 of the first end portion 11 and the strip 17 on the side of the lower surface 7 of the second end portion 12. The second part 9 and the third part 10 respectively bear the largest portion of the surface of the upper surface 6 between the strips 14 and 16, and of the surface of the lower surface 7 between the strips 15 and 17. They are constructed of materials lighter than that of the first part 8, for example in composite material or in polymer. They can be molded in the cavities of the first part 8. The blade 3 is both rigid thanks to the first part 8, resistant thanks to the end portions 11 and 12, and light thanks to the large volume of the second part 9. and of the third part 10. The areas of the upper surface 6 and the lower surface 7 which belong to the second part 9 and to the third part 10 perfectly extend the bands 14, 15, 16 and 17 and therefore give a continuous shape. and regular at the upper surface 6 and at the lower surface 7, and good aerodynamic quality at the blade 3. In other words, the second part 9 and the third part 10 each extend between the two end portions 11 and 12 and respectively bear a portion of the aerodynamic faces of the upper surface 6 and lower surface 7, which are positioned to ensure the continuity of said upper surface 6 and lower surface 7 faces with the bands 14, 15, 16 and 17 and complete said faces with said bands.

Other variant embodiments will now be described.

Figure 3 shows an alternative embodiment, which illustrates a core 23 of the first part, now 22, the thickness of which is uniform in the direction of elongation X, but otherwise similar to the embodiment of Figure 2. Compared to blades such as embodiments of US 3,294,366 A, it is therefore proposed here to make the junction core of the end portions oblique through the thickness dimension of the blade, along its dimension. length. This new design makes it possible to reinforce the vane by stiffening it more (it would be possible to reinforce this effect by giving the web a meandering curved shape or transverse ribs for example) and by increasing the cohesion of the second and the third part, whose tapered shape includes both a more massive portion at one end, and a softer portion at the opposite end, compared to parts whose thickness would be approximately constant. The thickness of the core can be scalable in the radial direction to take account of the aerodynamic forces undergone by the part. The core 13 may have an evolving shape depending on the section of the blade considered. This will be described more concretely by means of the following figures.

Consider three sections AA, BB and CC, shown in Figure 1 and taken at three different vane heights in the radial direction R, and compare them. In certain embodiments of the invention, shown in FIGS. 4A, 4B and 4C, the core, now 33, has a twisted shape, that is to say that its successive sections are deduced from each other by rotations around the radial direction R, which cause it to pass for example a shape similar to that of FIG. 3, where it joins the first end portion 31 at the lower surface and the second end portion at the extrados, in the reverse shape of FIG. 4C, where it joins the first end portion 31 at the extrados and the second end portion 32 at the intrados; intermediate shapes exist between these two heights, as shown in FIG. 4B, according to which the core 33 joins the two end portions 31 and 32 at approximately mid-thickness. In other words, the thicknesses b2 and e3 of the second part 34 and of the third part 35 of the blade are respectively decreasing and increasing (e2i and e3i) along a first radial section of the blade (CRI -CRI in Figure 1, taken in the radial direction R and the direction of thickness of the blade adjacent to the first end portion 31) in the outer radial direction (towards the outer platform 2); and the reverse is true along another radial section (CR2-CR2, adjacent to the second end portion 32), where the thicknesses e22 and e32 of the second part 34 and of the third part 35 are respectively increasing and decreasing in the outer radial direction.

Another possible construction is shown in Figures 5A, 5B and 5C, according to which the core, now 43, has a veiled shape tilting in the angular direction of the turbomachine, i.e. its successive sections are deduced from each other mainly by rotations in the axial direction: the direction of thickness of the blade: the web 43 is closer to the lower surface in FIG. 5A, closer to the upper surface in FIG. 5B, and even closer to the upper surface in FIG. 5C. In other words, the thicknesses e of the second part 44 are decreasing in the outer radial direction, and the thicknesses e3 of the third part 45 are increasing. In addition, this evolution is irregular along each section of the web 43: the position of the web 43 in the direction of thickness and along the height of the blade varies greatly near the first portion of end 41, and weakly, if at all, near the second end portion 42. Figures 7 and 8 illustrate this embodiment more fully.

Reverse evolutions are possible.

Such constructions of the core will in general be chosen for their resistance to static or aerodynamic forces, or their rigidity to vibrations, associated with the specific modes of the blade; they will be determined by tests or calculations on models.

Different and possibly more complex constructions than those which have been described here could also be proposed. It is thus that the evolving shape may relate to only a part of the core, a complementary part then having a regular shape in the radial direction R. The evolution of shape may be present only over a part of the height of the blade, for example over an area of 30% of the total height, or for example also in the area between the heights of 20% and 80% between the inner 1 and outer 2 platforms, at the heights of 0% and 100%.

There is also no rule about the thickness of the core, which may or may not be variable in the radial direction as well as in the perpendicular direction, for example thicker at the platforms (or more generally at the radial ends. ) that mid-height, or thicker at the connections to the end portions than at mid-length between these portions.

The adhesion of the second and third part to the third part can be obtained in various ways: by overmolding, by gluing or by interlocking prominent parts of the second and third part in corresponding concavities of the first part ( for example present on the posterior faces 18 and 19, as we have seen).

A completely different way to ensure the consistency of the blade consists in providing the core, for example the core 13, with holes 50 which allow the second part and the third part, for example 9 and 10, to join. directly, their material filling the bores 50. Overmolding is then a particularly suitable manufacturing process. FIG. 9 shows a construction with two radially and axially opposed bores 50, and FIG. 10 a construction with eight bores distributed in a regular rectangular network. The number, arrangement and width of the bores 50 are chosen according to the desired cohesion; like any variations in thickness at places less mechanically stressed, the holes also have the effect of lightening the core and therefore the blade. Figures 9 and 10 also show the embodiment of Figure 3, for which the core 13 has almost superimposable sections over the entire height, joining the first end portion 11 to the upper surface 6 and the second portion of end 12 to the lower surface 7, but similar bores could be made in all the other embodiments envisaged here.

Finally, it is not necessary for the web to join the end portions to the intrados or to the extrados: the second part and the third part can keep a non-zero thickness at these places, and at all heights. dawn, which has been represented by means of figure 6.

Claims

1. Blade comprising a reinforced leading edge, a trailing edge, and extending between the leading edge and the trailing edge while being limited by a lower surface face and an upper surface face which are two faces main aerodynamics of the vane, opposite in a direction of thickness (T) of the vane and each extending from the leading edge to the trailing edge; the blade being formed of a first part (8, 22), in one piece in a first material, composed of a first end portion (11) comprising the leading edge (4), of a second portion of 'end (12) comprising the trailing edge (5) and a web (13, 23) connecting the first end portion (11) to the second end portion (12), the first end portion and the second end portion each comprising a strip (14, 15, 16, 17) of each of the main aerodynamic faces (6, 7); of a second part (9), extending between the first end portion and the second end portion and joined to a main face of the core, in a second material lighter than the first material, and bearing a zone of a first of the main aerodynamic faces (6, 7) between the bands of said first aerodynamic face belonging to each of the end portions; and a third part (10, 30), joined to a second main face, opposite to the first main face, of the core, carrying a zone of a second of the main aerodynamic faces between the bands of said second aerodynamic face belonging to each of the end portions, and made of a material lighter than the first material; characterized in that the web (13) has, over at least a part of the height of the blade, an oblique extension in the direction of thickness, the second part (9) having a greater thickness near the second portion end than near the first end portion, and the third part (10) having a greater thickness near the first end portion than near the second end portion.

2. Blade according to claim 1, characterized in that the first end portion and the second end portion are connected to the core by rear faces (18, 19), opposite the leading edge and the edge. flight, essentially flat.

3. Blade according to any one of claims 1 or 2, characterized in that the core (13) is a rigid plate delimited by two main smooth faces (20, 21) and opposite.

4. Blade according to claim 3, characterized in that the plate has a variable thickness between the first end portion and the second end portion.

5. Blade according to any one of the preceding claims, characterized in that the second part and the third part are both constructed from the second material.

6. Blade according to any one of the preceding claims, characterized in that the first material is metallic.

7. Blade according to any one of the preceding claims, characterized in that the second material and the material of the third part are made of composite or polymer.

8. A blade according to claim 7, characterized in that the second part and the third part are molded or formed in the first part.

9. Blade according to any one of the preceding claims, characterized in that the first and the second end portion (11, 12) are massive and thicker than the core (13) in said thickness direction.

10. Blade according to any one of the preceding claims, characterized in that, in sections taken through the blade, in the radial direction of the blade and from the pressure side face to the pressure side face and on a part of height of the blade, one of the second part (44) and the third part (45) has an increasing thickness (es) in an outward direction of the radial direction, and the other of the second part and of the third part has a thickness (e2) decreasing in said outward direction.

11. Blade according to any one of claims 1 to 9, characterized in that, in a first section taken through the blade, adjacent to the first end portion, in the radial direction of the blade and of the face. from the intrados to the extrados face and over a part of the height of the blade, one of the second part (34) and of the third part (35) has an increasing thickness in an outward direction of the radial direction , and the other of the second part and the third part has a decreasing thickness in said outward sense; and, in a second section taken through the vane, adjacent to the second end portion, in a radial direction from the vane and from the lower surface face to the upper surface face and over a height portion of the vane. 'vane, said one of the second part and of the third part has a decreasing thickness in an outward direction of the radial direction, and said other of the second part and of the third part has an increasing thickness in said outward direction.

12. Blade according to any one of the preceding claims, characterized in that the second part and / or the third part has a thickness, at least over a part of the height of the blade, continuously decreasing towards zero in the direction of a end portions.

13. A blade according to any one of claims 10 or 11, characterized in that the height portion of the blade has an extension of at least 30% height; the height varying from 0% at a radially inner end of the vane to 100% at a radially outer end of the vane.

14. A blade according to claim 13, characterized in that the height portion of the blade extends between a height of 20% and a height of 80% between the radially inner and outer ends of the blade.

15. Blade according to any one of the preceding claims, characterized in that it comprises bores (50) through the core, by which the second part and the third part join.